<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>盒子模型-边框线</title>
    <style>
        div {
            width: 400px;
            height: 400px;
            background-color: red;
            /* 实线 */
            /* border: 2px solid #333; */
            /* 虚线 */
            /* border: 2px dashed green; */
            /* 点线 */
            /* border: 5px dotted orange; */
        }
    </style>
</head>

<body>
    <div>...</div>
</body>

</html>